Q&A: Who Is Revolving Relative to Whom? Earth vs. the Sun
Who Is Revolving Relative to Whom? Earth vs. the Sun
Question
Hello Rabbi,
I have a claim and I wanted to put it to the test here.
When people “say” that the Earth revolves around the sun, that isn’t absolute, right? I mean, it depends on the frame of reference, correct?
That is: is it equally correct to say that the sun revolves around the Earth when the frame of reference is the Earth, and then the model of this phenomenon would satisfy, of course, different equations than in the previous frame of reference—but with much greater complexity? And if that claim is correct, maybe one could say that the entire universe revolves around the Earth, with the equations for that model simply not yet having been developed because they are too complicated?
What I mean to ask is: does the complexity/simplicity of the model serve as an indicator of the model’s correctness? And if so, I’d be happy for a proof or other examples that support the claim or your hypothesis.
Best regards,
A Moroccan Baba 🙂
Answer
There is no question here of truth or falsehood. It really is just a choice of coordinate system. In physics people also talk about Mach’s principle and fictitious forces, but those are issues in dynamics. From a kinematic standpoint, there is no truth or falsehood to the question of who revolves around whom. And that is where all the wiseguys who quote Copernicus as if he discovered something go wrong. He discovered a system in which the description of the motion is simpler. That’s all.
See my article here: https://www.knowingfaith.co.il/%D7%AA%D7%95%D7%A8%D7%94-%D7%95%D7%9E%D7%93%D7%A2/%D7%94%D7%A7%D7%95%D7%A1%D7%9E%D7%95%D7%9C%D7%95%D7%92%D7%99%D7%94-%D7%94%D7%9E%D7%A7%D7%A8%D7%90%D7%99%D7%AA-%D7%94%D7%90%D7%9D-%D7%94%D7%A2%D7%95%D7%9C%D7%9D-%D7%94%D7%95%D7%90-%D7%A2%D7%92%D7%95%D7%9C
Discussion on Answer
It is a scientific fact that the Earth revolves around the sun and not vice versa. The reason is that two bodies moving relative to one another revolve around their common center of mass. The mass of the sun is greater than that of the Earth by hundreds of thousands of times, and therefore the center of mass of the Earth and the sun is inside the sun (!) The meaning of this in physics is that the sun is stationary relative to the Earth, which means that the Earth revolves around the sun.
As a physicist, you display an impressively poor understanding. Though, to be fair, the confidence that accompanies it is also very impressive. The center of mass is nothing more than another coordinate system, no different from any other.
Beyond that, when people talk about Copernicus’s coordinate system, he did not say that the Earth and the sun revolve around their common center of mass (that was long before the two-body problem was solved). He said that the Earth and the other planets revolve around the center of the sun. And that is what people mean today as well.
Long live science!
I didn’t understand.
If there were only the Earth and the sun, wouldn’t it be possible to see which one revolves around which?
That is to say, either the sun revolves
around the Earth,
or the Earth revolves around itself.
So now it’s also impossible to see
that one is right and the other is wrong?
What am I missing here?
To Anonymous,
No. It simply means that there is relative rotational motion between them, and that’s it. Just like with motion in a straight line, where we talk about relative motion between two bodies at a certain speed. You can decide which of them is moving and which is standing still, or whether both of them are moving. The main thing is that the relative speed between them remains the same speed.
I liked the article. Thanks.